Yesterday, French police arrested the terrorist accused of murdering three Jews in Brussels, Belgium on the eve of the European elections. The killer, 29-year old French citizen Mehdi Nemmouche, a son of Muslim immigrants, had gone to Syria in 2013, where he joined the rebels against President Bashar al-Assad and was trained as a jihadist.

On Saturday afternoon, May 24, Nemmouche walked into the Jewish Museum in Brussels, armed with a pistol and a Kalashnikov assault rifle. He killed three Jews, including two Israeli tourists, and seriously wounded another, who is still fighting for his life in hospital. Then Nemmouche calmly walked out of the museum.

During the past three years, thousands of young Islamic immigrants from France, Germany, Britain and all other European countries, as well as young Western Islamic converts, have gone to Syria, where they trained to be killing machines. Some of them have returned home, where they now constitute the biggest threat to domestic security in decades.

French authorities were able to capture Nemmouche within a week because they had his name on a list of returned Syria fighters. Having his name on a list of jihadists, however, was not able prevent him from committing murder in neighboring Belgium.

Police also apparently believe that Nemmouche filmed his terror attack with a camera which he had on him. The Kalashnikov, the pistol and the camera were found in Nemmouche’s possession when he was arrested. The previous anti-Semitic murders in Europe were also committed by a terrorist with a camera. In 2012, Mohammed Merah, a French Islamist of Algerian descent, murdered a rabbi and three children outside a Jewish school in Toulouse, in southern France. Both Merah and Nemmouche were caught before they were able to upload the images of the deed. They may have wanted these films to serve as tools for jihadist propaganda, recruitment and instruction.

Nemmouche and Merah were both French citizens; France has the largest community of Muslim immigrants in Western Europe. In countries such as the Netherlands and Belgium, the authorities seem to be increasingly concerned that the returned Syria fighters pose an enormous security risk. Rob Wainright, director of the European law enforcement agency Europol, warned in his 2013 annual report that the returned Syria fighters could incite others to join the armed struggle in Syria, as well as use their training, combat experience, knowledge and contacts to conduct such activities within the EU.

Last Saturday, Europol released its EU Terrorism Situation and Trend Report 2014 in which it repeats that «there is a growing threat from EU citizens who, having travelled to conflict zones to engage in terrorist activities, return to the European Union with a willingness to commit acts of terrorism … This phenomenon may result in terrorist attacks with unexpected targets and timings.»

The ease with which Nemmouche was able to carry out his assault has frightened many all over Europe. How is it possible that this man, who was known to be a terrorism risk, could acquire an automatic rifle and take the weapon into the Jewish Museum? Why had he not been followed? Obviously such a practice is not feasible for all criminals, but for known jihadists? Had his phone and internet chats been tapped? It would be also be helpful, albeit unfortunately, if owners of buildings seemingly at risk invested in security guards and metal detectors for their entrances.

There are also political questions. Why had Nemmouche even been allowed to return to France after his stay in Syria? Britain strips immigrants holding dual nationality, who go to Syria to fight, of their British nationality. This act allows the British authorities to ban them from re-entering the country or have them expelled after their return them when the authorities have proof that they went to Syria to fight. «Citizenship is a privilege, not a right, and the home secretary will remove British citizenship from individuals where she feels it is conductive to the public good to do so,» the British authorities stated last December.

Why have the French not done the same?

The problem affects not only European countries. American and Australian Muslims are also known to have travelled to Syria to join jihadist groups fighting the Assad regime. Russia is also familiar with the problem: more than a year ago, the head of the Russian Federal Security Service, Alexander Bortnikov, warned that the return of Russian Syria fighters will pose a terrorist threat.

It remains to be seen in what way the Western authorities react to this threat. So far, the signs are not encouraging. The Belgian authorities used — or rather abused — the murderous attack in Brussels to indoctrinate the public with multiculturalist propaganda.

Last week, for example, Brussels school children were given special lessons to warn against anti-Semitism and racism. The way to combat this, Yvan Mayeur, the Socialist Mayor of Brussels, said, was «to give room to the many cultures and religions in Europe.» He said that his city needed more «diversity.» But diversity does not mean diversity any more. Diversity is now the new code word for more Islam. Other politicians advocated punishing «hate crimes» more severely. But hate crime does not mean hate crime any more. It is now the politically-correct European «newspeak» code word for criticism of Islam.

So, rather than arming itself against the Islamist threat, the West still remains blind to the threat, while terrorists such as Merah and Nemmouche carry on killing Jews — and others.